1. Field of the Invention
The invention relates to electrochemical detection. More particularly, the invention relates to systems and methods of multiplexed electrochemical detection of samples using sample analysis containers and associated instrumentation.
2. Description of the Related Art
Molecular biology utilizes a wide variety of techniques to detect and identify the molecular structure of a sample. In particular, sequence analysis of DNA or RNA samples is performed to detect gene sequences, detect mutations in gene sequences, or detect expression levels of genes. Such sequence analysis is useful for diagnostic purposes as well as to facilitate genetic research and pharmaceutical development.
Sequence analysis can be performed by hybridizing a sample to polymer probes having known sequences. One method to detect nucleic acid hybridization is to detect a quantity of counterions surrounding the nucleic acid. Accordingly, hybridized nucleic acid tends to be surrounded by more of the counterions than would single stranded nucleic acid. The counterions are typically detected by an electrochemical reaction, for example by reduction of a trivalent ion to divalent; in this way, the counterions function as an electron transfer species.
Electrochemical quantitation is described in A. B. Steel et al., Electrochemical Quantitation of DNA Immobilized on Gold, Anal. Chem. 70:4670-77 (1998), hereby expressly incorporated by reference in its entirety. In this publication, Steel et al. describe the use of cobalt (III) trisbipyridyl and ruthenium (III) hexaamine as species which interact with surface-immobilized DNA.
The continuing development of sequence analysis as a tool for diagnostic purposes as well as genetic research and pharmaceutical development necessitates improvements in sequence analysis systems. The sequence analysis systems need to be flexible to allow testing of different batch sizes, reliable to allow repeatable test results, and low cost in order to facilitate the use in such diagnostic procedures such as patient sample screening.